| 1. |
- Andrade, Pedro, et al.
(författare)
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Structural Behaviour of a Novel Column-Splice Joint : Finger Connection
- 2015
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Ingår i: The 13th Nordic Steel Construction Conference. - Tampere : Tampere University of Technology, Department of Civil Engineering. - 9789521535789 - 9789521535796 ; , s. 215-216
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Konferensbidrag (refereegranskat)abstract
- The novel joint presented in this paper is a friction connection used for column-splice connections of modular buildings as part of the innovative construction method introduced in the research project Optimization of frames for effective assembling - FRAMEUP. This type of joint provides a quick assembly and can deal with misalignments by introducing a connection gap. A filler and finger plate are welded to the upper part of the column to this end.The gap between finger plates and lower column faces is closed during tightening of the bolts and, thus, establishes a slip-resistant connection. The efficiency of the joint resistance based on different connection gaps subjected to uniform compression is assessed.The column-splice is composed of four slip-resistant connections, one at each side of the tube. Each finger plate consists of three long slotted holes and is welded to the upper column face. Long slotted holes are used to accommodate vertical misalignments and, therefore, allow fitting the bolts which are pre-installed in the lower column. Filler plates with different thicknesses (4, 6 and 8 mm) welded between the finger plate and upper column face are used to create a connection gap which allows balancing horizontal misalignments. The lower column faces consist of each nine holes with no clearance in order to pre-fit the bolts in a workshop. Thus, the assembling process on the construction site can be speeded up as once the lowercolumns are in place all bolts can be tightened immediately.
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| 2. |
- Pavlović, Marko, et al.
(författare)
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Calibration of the Ductile Damage Material Model Parameters for a High Strength Steel
- 2015
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Ingår i: The 13th Nordic Steel Construction Conference. - Tampere : Tampere University of Technology, Department of Civil Engineering. - 9789521535789 - 9789521535796 ; , s. 231-232
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Konferensbidrag (refereegranskat)abstract
- The on-going RUOSTE project aims to improve understanding of HSS by means of tests and FEA, addressing issues of ductility and stability of structures made of HSS. Various material models used in FEA are verified by tests. This paper presents calibration and verifica-tion of ductile damage material model in Abaqus FE software package referring to series of tensile test experiments on coupons and plate specimens with a single circular hole. Nominal steel grade S700MC and S960Q are used. Damage initiation criterion and evolution law are derived analysing localization of plasticity by FEA. Quasi-static analysis using explicit dy-namic solver is chosen in order to create the most realistic FEA of the specimens.
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| 3. |
- Pavlovic, Marko, et al.
(författare)
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Connections in towers for wind converters : part I: Evaluation of down-scaled experiments
- 2015
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Ingår i: Journal of constructional steel research. - : Elsevier BV. - 0143-974X .- 1873-5983. ; 115, s. 445-457
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Tidskriftsartikel (refereegranskat)abstract
- The cost of a tubular steel tower supporting a wind converter becomes increasingly important in a competitive energy market. In-situ connection between tower segments is an important factor of the design. The tower segments are usually connected by welded ring flanges. An alternative solution based on a novel single lap friction connection is analysed. The purpose of the research presented in this paper is to thoroughly analyse the behaviour of both connections by an experimental testing programme and advanced finite element analysis (FEA). Down-scaled experiments of ring flange and friction connection in circular towers were performed using a 4-point bending test set-up. Altogether eight connections joining cylindrical shell, 1 m diameter, plate thickness 8 mm and total span of about 7 m were tested. A friction connection with long open slotted holes and two different cases of the ring flange connection are considered: with perfectly flat flanges and flanges with geometric imperfection. Results of advanced quasi-static FEA, using explicit dynamic solver and ductile damage material model for bolts, are compared to experiments. Failure modes, bolt forces and distribution of meridional membrane stresses in the shell in the vicinity of connections are analysed. Existing hand-calculation models, for the bolt force and normal stress distribution in the shell are validated by experiments and FEA.
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| 4. |
- Pavlovic, Marko, et al.
(författare)
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Connections in towers for wind converters : Part II: The friction connection behaviour
- 2015
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Ingår i: Journal of constructional steel research. - : Elsevier BV. - 0143-974X .- 1873-5983. ; 115, s. 458-466
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Tidskriftsartikel (refereegranskat)abstract
- A novel friction connection consisting of a single lap joint with long open slotted holes is proposed for use in tubular towers for wind converters for in-situ connections. This is a competitive alternative to the common ring flange connection as it has been shown in the European Project “HISTWIN”. Two sets of experiments are analysed: the down-scaled tubular steel tower 4-point bending experiments using high-strength bolts M20 and a single lap joint using plate thickness 25 mm and tension control bolts M30.The main motivation for this paper is a much higher bending resistance obtained in the 4-point bending experiments compared to predictions based on hand-calculation models.Results of experiments are used to validate finite element analysis (FEA). Explicit solver and the most realistic geometry of the bolts are the main characteristics of the FEA performed. Very good agreement between the experiments and FEA results is obtained, which provides credibility of the computational approach used to thoroughly examine experimental results. New evidences of the friction connection behaviour are provided: a short-term loss of preloading force due to external loading, transfer of shear force in the single lap joint and influence of the slotted hole on the joint resistance.Results obtained from hand-calculation models are used to predict the loss of preloading, the bending resistance of the connection and meridional stresses in the tower shell in the vicinity of the connection, which are compared to the experiments and the FEA. Recommendations related to use of the hand-calculation models in the design are provided.
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| 5. |
- Pavlović, Marko, et al.
(författare)
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Friction connection vs. ring flange connection in steel towers for wind converters
- 2015
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Ingår i: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 98, s. 151-162
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Tidskriftsartikel (refereegranskat)abstract
- Tubular steel towers are the most commonly used structures to support wind converters. Towers are fabricated in welded segments, complying with the traffic requirements for transportation, and in-situ assembled. Ring flange connections are used to connect two segments. Fatigue endurance of the ring flange to the shell weld, class 71, is often the design criterion and imposes a limit on the shell thickness. Recently studied friction connections with long opened slotted holes, in HISTWIN and HISTWIN2 projects, provides a remedy for this limitation. The main purpose of this paper is to compare performance of the ring flange connection and the novel friction considering connection of a real tubular tower segment 3.37 m in diameter and 24 mm shell thickness. This cross-section is designed for the ultimate load MEd = 45.8 MNm and the steel grade S355. Finite Element Method is used to investigate possible failure modes of the connection. Advanced FEA comprise the realistic geometry of the connection, ductile damage material model and element removal using explicit dynamic solver. This allows sophisticated analysis of the behaviour and direct comparison of the results for both connection alternatives. The FEA is validated by down-scaled experiments performed previously within the HISTWIN project. The friction connection is thoroughly examined: geometry of the connection, influence of the shell imperfection in the vicinity of the connection and possible use of higher resistance steel grades. By focusing on key issues of the friction connection recommendations for the design are provided together with a numerical example.
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